1. Field of the Invention
The present invention relates to a construction machine provided with a heat exchanger for cooling e.g. engine cooling water, a duct for guiding air to cool the heat exchanger, and an air cleaner for filtering engine inlet air.
2. Description of the Background Art
The background art of the invention will be explained by describing a hydraulic excavator shown in FIG. 3 and FIG. 4, as an example.
The hydraulic excavator has an upper slewing body 1, which is provided with an engine room 4 at a rear part thereof. The engine room 4 is covered with a guard member such as an engine guard 2 and a counterweight 3, accommodating therein an engine 5, a hydraulic pump 6, a heat exchanger 7, a cooling fan 8, a duct 13, and an air cleaner 16.
The engine 5 is disposed in a posture extending laterally, that is, in left and right directions. The hydraulic pump 6 is disposed on one of the lateral sides of the engine 5 (on the right side in FIG. 3 and in FIG. 4), and the heat exchanger 7 is disposed on the other of the lateral sides (on the left side in FIG. 3 and in FIG. 4) to cool a fluid to be cooled (e.g. engine cooling water). The cooling fan 8 sucks the external air into the engine room 4 to draw the external air through the heat exchanger 7.
In the engine room 4, there is formed an air inlet chamber 9 for drawing the air sucked by the cooling fan 8 to the air inlet side of the heat exchanger 7. The counterweight 3 has left and right side portions 3a and 3b, disposed so as to locate the side portions 3a and 3b at the lateral sides of the engine room 4 and make the left side portion 3a define the air inlet chamber 9. Each of the side portions 3a, 3b is formed with a window-hole like maintenance opening 10, and a maintenance panel 11 to open and close the maintenance opening 10. The part of the side portions 3a, 3b which part surrounds the maintenance opening 10 and the maintenance panel 11 in a closed state define a recess 12 in an inner portion of the maintenance panel 11.
The duct 13, which is adapted to guide the external air sucked by the cooling fan 8 to the heat exchanger 7, has a box-like shape with a main wall 13b disposed upstream of the heat exchanger 7 and a front wall 13a located on the air inlet side of a core surface 7a of the heat exchanger 7 to face the core surface 7a. The engine guard 2 is formed with a first air inlet 14 for drawing the external air into the air inlet chamber 9 therethrough, in the region constituting a top wall of the air inlet chamber 9 and the front wall 13a of the duct 13 is formed with a second air inlet 15 attached with a not graphically shown filter. The first and second air inlets 14 and 15 and the main wall 13b of the duct 13 define an inlet passage turning in an L-shape so as to shift the direction of external air introduced downward through the first air inlet 14 to a lateral direction through the second air inlet 15 to thereby apply the external air onto the core surface 7a of the heat exchanger 7. Besides, downstream of the heat exchanger 7a, a fan shroud 23 is interposed between the heat exchanger 7 and the cooling fan 8.
The air cleaner 16, which is adapted to filter the engine inlet air, is formed into a substantially tubular shape. The air cleaner 16 is disposed in the air inlet chamber 9. In detail, the air cleaner 16 is disposed in a lateral posture extending longitudinally, that is, in front and rear directions, inside the duct 13, in the same manner as disclosed in Japanese Unexamined Patent Publication No. 2006-206034.
The upper slewing body 1 has an upper frame 17 as a base thereof and a cabin 18 disposed at a front left part of the upper frame 17. The “left and right directions” and the “front and rear directions” described below indicate respective directions viewed from an operator seated in the cabin 18.
The background art described above has a drawback that the air cleaner 16 disposed in the duct 13 interferes with a smooth air flow (cooling air) directed from the second air inlet 15 toward the core surface 7a of the heat exchanger 7. Specifically, the air sucked into the air inlet chamber 9 is deflected into a part of the core surface 7a so as to avoid the air cleaner 16, which lowers the air sucking efficiency and causes a shortage in the air volume required for the heat exchanger 7 to thus lower the cooling performance of the heat exchanger 7. Besides, increasing the speed of the cooling fan 8 to secure the required air volume for the heat exchanger 7 may increase the operating sound of the cooling fan 8 and raise the level of noise leaking to the outside. This causes a requirement of improved measures against the noise, resulting in increased cost.